For decades, a gruesome parasite threatened American livestock. The New World screwworm, whose name comes from the way its maggots twist and drill into the living flesh of warm-blooded animals, caused hundreds of millions of dollars in livestock losses across the southern and southeastern United States. Today, that same pest has been completely wiped from the country, and scientists credit a surprisingly clever trick of nature for the victory.
May Berenbaum, an entomology professor at the University of Illinois, recently explained how this worked in an interview. The key is something called the sterile insect technique, developed about 60 years ago. Here is how it operates: scientists raise huge numbers of screwworm flies in laboratories. They then expose the males to radiation that makes them unable to father offspring. When these sterilized males are released into the wild, they can still mate with female flies. But because female screwworm flies mate only once in their entire lives, any female that pairs with a sterile male will never produce any babies. Release enough sterile males, and most females end up wasting their single mating opportunity on a male who cannot father young. The population collapses.
This approach has no known harmful effects on the environment, making it a remarkably clean tool for pest control. It worked so well that the United States declared the New World screwworm eradicated from its territory. The same method has helped eliminate the pest from several other countries as well.
Berenbaum notes that the success did not come from luck. It grew out of decades of basic research into how insects reproduce. Early scientists discovered that radiation could make certain male insects sterile. Other researchers then uncovered the critical detail that female screwworm flies mate only once, which meant flooding an area with sterile males was a guaranteed way to break the reproductive cycle.
Interestingly, Berenbaum cautions against constantly releasing sterile males as a preventive measure. She argues that doing so could actually speed up the evolution of resistance, where the flies adapt to overcome the technique and make it useless. Sometimes, waiting for a problem to emerge and then responding is the smarter strategy.
Berenbaum also offered straightforward advice for scientists who want the public to understand and support basic research: be willing to talk to journalists. That kind of openness, she suggests, helps people see why studying insects matters, even when the practical benefits are not immediately obvious.
The screwworm story stands as proof that patient scientific inquiry, even into topics that seem obscure, can yield powerful tools for solving real-world problems.